An FED is a cathode-ray tube (CRT) panel having a large number of microscopic electron guns of micron size arranged corresponding to each of pixels.
Since the FED, in which the electron guns are driven in each of the pixels independently of each other, requires no scan of an electron beam over a wide angle range unlike the CRT panels, it is a display far thinner and flatter than the CRT panels (e.g., reference should be made to JP-A-07-230776). Particularly, the FED is expected as a large-screen flat display of at least 40 inches, which is hardly realized by the CRT panels.
In the FED, an anode panel with phosphors faces an emitter panel with emitters for emitting electrons, through a plurality of spacers, and the periphery of the anode panel and emitter panel is sealed with a glass paste or the like.
The internal space of FED, i.e., the space between the anode panel and the emitter panel facing each other is typically in a high vacuum state of 10−3−10−5 Pa, and electrons emitted from an emitter of the emitter panel into the space impinge upon a phosphor of the anode panel to induce electron beam induced luminescence. As a result, a pixel to which the phosphor belongs develops a color.
The distance between the anode panel and the emitter panel facing each other is typically 1-2 mm, and, in order to keep the distance independently of the pressure difference between the atmospheric pressure and the pressure of the internal space (e.g., 10−3−10−5 Pa), the spacers are interposed between the anode panel and the emitter panel, as described above. The conventional spacers were made of alumina.
The spacers of alumina were likely to be charged with electrons, which raised the problem that the display image tended to be distorted.
The Inventors of the present invention previously have invented the glass containing 40-80 mol % SiO2, 1-20 mol % Al2O3, 15-50 mol % Li2O+Na2O+K2O, 0-10 mol % TiO2, and 0-10 mol % ZrO2 for spacers capable of preventing the charging.
The glass has a low resistivity and the spacers made thereof have the resistance low enough to effectively prevent the charging. However, the glass is an ion-conducting glass containing an alkali metal oxide at least 15 mol % and the resistance of the spacers might increase as a lapse of time. Namely, application of an electric field brings about polarization in the spacers, so that the resistance of the spacers can increase.
An object of the present invention is to provide a glass which has a low alkali metal oxide content and which is resistant to polarization under application of an electric field in use as spacers, a method for its production, and an FED.